Process for improving cotton fabrics



UNITED STATES' PA TENT orrlclz.

cus'mv Anom- Bossmnn, or new, swr'rznanm, ASSIGNOR To run 1mm a-o.snnmn'r, IBLEICEEREI, FILIALE Aaron, or mean, swrrznamnn.

k rnocnjss rorv mrnovme corron FABRICS.

No Drawing.

To all who m it may concern:

Be it known that I, G STAV AnoLr Boss- HARD, a citizen of the Republicof Switzerland, residing at Rebenstrasse 44, Arbon, Switzerland, haveinvented certain new and useful Improvements in Processes for I111-proving Cotton Fabrics; and I do hereb declare the following to be aclear, ful,

and exact description of the invention, such as will enable othersskilled in the art to which it appertains to make and use the same;

It is a well known fact that the action of concentrated mineral acids oncotton fabrics causes the latter to assume a transparent parchment-likeappearancea Mercer observed in 1844 that concentrated sulfuric acid offrom 49.5to 555 B. produces the above mentioned'eflfect'on cotton. Lateron ithas been established that transparent' effects on cotton fabricsmay be obtained by treating the fabrics-alternately or subsefiuentlywith sulfuric acid of from 49 to 51 and with concentrated alkaline lyes.

place sulfuric acid of from 49 to cooled hydrochloric acid of a specificgravity of 1.19, or by nitric acid ofefrom 43 to 46 B.,, or by azinc-chlorid solution of 66 1%. at a temperature offrom 60 to 70 C. orby a solution of -cupric ammonia;

, If nitric acid'of a concentration of more than 423 B. (spec. gravityof 1,415) or sulfuric acid' of a concentration of more than 49 B. (spec,gravity of 1,515) be caused to act on cotton a process takes place whichsimilar to the mercerizing by means of concentrated alkaline lyes andwherein a swelling of the fibers, shrinkage -and increase of strengthtakes place. Bleached and mercerized cotton fabrics which are treatedwith such an acid assume a gelatinous parchment like appearance and showa considerably stronger aflinity to direct actin coloring matters. Knecht, 37459, 1904 Jom'n. Soc. Dyers "and 0020mm 1896,89, fia'rberzemm95/96 401) the treatment with nitric acid-of 423 Be. or more causesbesides a weak nitrification, the formation of a very unstablecellulose-ester which decomposes b the action of the water similar to anal aline cellulose. If nitric acid of a specific gravity of above 1,415(423 B.), or sulfuric acid of a specific gravity of above sulfuric acidof from to 58 Furthermore it is already known to re- According to 1,51549 B.) is

Specification of Lettersllatent. Patented N 1, 1921, Application filedJuly 9, 1920. Serial No. 395,101.

caused to act on bleached or'mercerized cotton fabrics. these fabricsassume after a short time a gelatinous parchment-like appearance andafter a strong tentering 2". e.

stretching with jigging motion of the treated fabrics theyassume atransparent appear- The present invention is servation, that the abovenous, parchment-like or transparent efi'ects of. strong nitric acid orsulfuric acid on based on the obbleached or mercerized cotton fabricsare considerably increased if, instead of using such an acid separatelacid of from 48 to 504 and cooled down to 0 C. or below 0 C'. is usedthat is a "liquid obtained by mixing nitric acid of from C.) and v 40 to41 B. (at a temperature of 15 B. (at a temperature of 15 (1.).

If a nitro-sulfuric acid cooled down to 0 C. or below 0 C. within the:lower limit of minus 20 C. and consisting of 1- part by volume ofsulfuric acid of from 55 to 58 B. and 1 part by volume ofnitric acid offrom 40 to 41 B. is caused to act upon a bleached or mercerized cottonfabric the fabric assumes after 5 seconds a gelatinous parchment-likeappearance whereby the fibers swell and shrink in the longitudinal andtransverse directions. The above described morphological modificationsof the fabric can be varied at will by using nitrosulfate acids ofdifferent concentration. r If a concentrated nitro-sulfuric acidcomposed of for instance 1 part by volume of sulfuric acid of 57 B. and1 part by volunie of nitric acid of 41 B. is used strong parchment-likeeiiects result which after a tentering or stretching with jigglng motionof the treated fabric change over into transparent effects which may beincreased by a subsequent mercerizing of the treated fabric.

If bleached or mercerized cotton fabrics are printed on with reservesthe treatment of these fabrics with concentrated nitrosulfuric acidallows of obtaining transparcnt pattern efiects. It will ,be noted thatthe treatment of the fabric takes place at temperature below atmospherictemperatlfi'fe and while the fabric is kept stretched. By. controllingthe temperature and keeping it low the character of the transarentifabric can described gelati a nitro-sulfuric higher temperaturesto a soft feeling fabric at the lower temperatures. On the other hand,if the concentration be but slightly lowered with a correspondingincrease in the length of time required for nitration by reason of thelesser concentration, wool-like effects will be obtained, the fabric inthis instance not being strongl stretched to allow free deformation of te fibers.

I claim:

1. In the process of producing transparent efiects of cotton fabrics,treating the fabric while stretched to nitro-sulfuric acid at atemperature below atmospheric temperature. v

2. In the process of producing transparent efiects of cotton fabrics,treating the fabric while stretched to nitro-sulfuric acid attemperatures below zero degrees centigrade.

3. The step in the process of producing transparent efiects of cottonfabrics which comprises subjecting the fabric to the action ofnitro-sulfuric acid cooled from zero degrees to minus twenty degreescentigrade and obtained by mixing equal volumes of sulfuric acid of notless than 57 B and nitric acid of not less than 41 B.

4. In the process of producing transparent cotton fabrics, treating thefabric While stretched to nitro-sulfuric acid of from 48.3 to 505 B. ata temperature not over zero degrees centigrade.

5. The process of improving cotten fabrics, which comprises treating thefabric while stretched to the action of a mixture of equal parts ofsulpuric acid of not less than 57 B. and nitric acid of not less than 40B. at a temperature below zero degrees centigrade, and subjecting thefabric to subsequent mercerization.

6. The process, which comprises subjecting a cotton fabric, whilestretched, to nitrosulfuric acid at a temperature 0 C., and subsequentlymercerizing the fabric.

In testimony that I claim the foregoing as my invention, T have signedmy name.

ens'rav ADQLF BOSSHARD.

